This invention relates in general to the detection of microorganisms, and more specifically to a machine for automatically analyzing specimens which have been introduced into media-containing cards so as to determine the presence of specific microorganisms in the card or to determine the effects of known antibiotics on such microorganisms.
The detection and identification of microorganisms is an important aspect of medical science which has heretofore been characterized by difficult and time consuming procedures requiring highly skilled personnel. For example, the conventional procedure for detecting and identifying a microorganism requires collecting a specimen on a swab and then wiping the swab over a nutrient surface. After incubating the culture medium for at least 24 hours, it is examined for pure colonies of microorganisms, but usually the initial incubation yields only a large biomass. A meaningful evaluation cannot be made until pure colonies are isolated, and this usually requires dilution and further incubation. Furthermore, it is often necessary to verify an identification by conducting biochemical tests on the isolated colonies. The time between sampling and identification typically ranges between two and three days.
When prescribing medicines and antibiotics, it is often necessary to know the identity of the microorganism causing illness. Indeed, the isolated colonies are subjected to various antibiotics to determine the susceptibility of the isolated microorganisms to the antibiotics. Current procedures do not provide an identification for several days, and usually the time expended in making the identification coincides with the most critical period of illness.
U.S. Pat. application Ser. No. 461,249 of C. Aldridge et al, filed Apr. 16, 1974, now U.S. Pat. No. 3,963,355 discloses a system for reducing the time required to identify microorganisms to about 13 hours or less. That system however is incapable of performing high volume screening.